Cannula having nitinol reinforced inflow region

Abstract

An intravascular heart pump assembly can include a rotor with at least one impeller blade, and a cannula. The present application describes various cannulas that can be manufactured from multiple layers of material to improve flexibility, manufacturability, and durability without increasing an outer diameter of the cannula. In one embodiment, the cannula includes an inflow section having a sheet formed of a shape memory material embedded within a polymer and having at least one lateral hole or aperture in the inflow section. The at least one lateral hole is defined by a first hole in the sheet and a second hole in the outer polymer layer of the cannula. The first hole and the second hole overlap so that blood can enter the cannula through the holes.

I claim: 
     
       1. An intravascular heart pump assembly comprising:
 an elongate catheter having a proximal end configured to be positioned outside of a patient's body and a distal end configured to be positioned in an artery proximate to a patient's heart; 
 a rotor having at least one impeller blade coupled to the distal end of the elongate catheter; 
 a motor operatively coupled to the rotor; and 
 a cannula having a proximal end and a distal end, the proximal end coupled to the distal end of the elongate catheter, the cannula comprising:
 a cannula body having a proximal region and a distal region, the distal region having at least one lateral inflow hole, and the proximal region having at least one lateral outflow hole, 
 a sheet formed of a shape memory material and embedded within a polymer, the sheet and the polymer forming the cannula body, and 
 in the distal region, the at least one lateral inflow hole being defined by a first layer having a hole in the shape memory material sheet and by a second layer having a hole in the polymer, wherein the hole in the first layer and the hole in the second layer overlap along an external surface of the cannula. 
 
 
     
     
       2. The heart pump assembly of  claim 1 , wherein an outer perimeter of the hole in the second layer is within an outer perimeter of the hole in the first layer. 
     
     
       3. The heart pump assembly of  claim 2 , further comprising at least one slitted opening disposed in the sheet configured to allow the sheet to flex. 
     
     
       4. The heart pump assembly of  claim 3 , wherein the cannula further comprises a coil formed of a shape memory material. 
     
     
       5. The heart pump assembly of  claim 4 , wherein at least a portion of the coil is positioned proximal to the shape memory material sheet. 
     
     
       6. The heart pump assembly of  claim 4 , wherein at least a portion of the coil is positioned distal of the shape memory material sheet. 
     
     
       7. The heart pump assembly of  claim 4 , wherein the shape memory material is nitinol. 
     
     
       8. The heart pump assembly of  claim 7 , wherein the cannula body is formed of two polymer layers having the shape memory material sheet embedded in between the two polymer layers. 
     
     
       9. The heart pump assembly of  claim 1 , wherein the at least one lateral outflow hole is proximal to or aligned with the rotor. 
     
     
       10. The heart pump assembly of  claim 9 , wherein the proximal region including the at least one lateral outflow hole comprises a non-memory alloy having a plurality of lateral outflow holes. 
     
     
       11. The heart pump assembly of  claim 10 , wherein the proximal region including the at least one lateral outflow hole is formed from stainless steel. 
     
     
       12. The heart pump assembly of  claim 1 , further comprising a flexible projection coupled to a distal end of the cannula. 
     
     
       13. The heart pump assembly of  claim 1 , wherein the distal region includes a plurality of lateral inflow holes. 
     
     
       14. The heart pump assembly of  claim 13 , wherein the distal region further comprises a second lateral inflow hole positioned proximal to the at least one lateral inflow hole. 
     
     
       15. The heart pump assembly of  claim 1 , wherein the cannula body has an outer diameter of less than or equal to about 22 Fr. 
     
     
       16. The heart pump assembly of  claim 1 , wherein the shape memory material sheet is less than or equal to 0.07 mm thick.